Mortgage Loans - Loan Restructuring - Subsequent Default (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2024	Mar. 31, 2023
Loans in Mortgage Portfolio [Line Items]
Restructured loans, amortized cost, subsequent default	$ 1,439	$ 1,313
Payment Deferral
Loans in Mortgage Portfolio [Line Items]
Restructured loans, amortized cost, subsequent default	917	810
Payment Delay and Term Extension
Loans in Mortgage Portfolio [Line Items]
Restructured loans, amortized cost, subsequent default	497	204
Payment Delay, Term Extension, Interest Rate Reduction and Other
Loans in Mortgage Portfolio [Line Items]
Restructured loans, amortized cost, subsequent default	25	299
Single-family
Loans in Mortgage Portfolio [Line Items]
Restructured loans, amortized cost, subsequent default	1,434	1,313
Single-family | Payment Deferral
Loans in Mortgage Portfolio [Line Items]
Restructured loans, amortized cost, subsequent default	917	810
Single-family | Payment Delay and Term Extension
Loans in Mortgage Portfolio [Line Items]
Restructured loans, amortized cost, subsequent default	497	204
Single-family | Payment Delay, Term Extension, Interest Rate Reduction and Other
Loans in Mortgage Portfolio [Line Items]
Restructured loans, amortized cost, subsequent default	20	299
Single-family | 20- and 30-year or more, amortizing fixed-rate
Loans in Mortgage Portfolio [Line Items]
Restructured loans, amortized cost, subsequent default	1,376	1,250
Single-family | 20- and 30-year or more, amortizing fixed-rate | Payment Deferral
Loans in Mortgage Portfolio [Line Items]
Restructured loans, amortized cost, subsequent default	871	766
Single-family | 20- and 30-year or more, amortizing fixed-rate | Payment Delay and Term Extension
Loans in Mortgage Portfolio [Line Items]
Restructured loans, amortized cost, subsequent default	490	200
Single-family | 20- and 30-year or more, amortizing fixed-rate | Payment Delay, Term Extension, Interest Rate Reduction and Other
Loans in Mortgage Portfolio [Line Items]
Restructured loans, amortized cost, subsequent default	15	284
Single-family | 15-year or less, amortizing fixed-rate
Loans in Mortgage Portfolio [Line Items]
Restructured loans, amortized cost, subsequent default	29	27
Single-family | 15-year or less, amortizing fixed-rate | Payment Deferral
Loans in Mortgage Portfolio [Line Items]
Restructured loans, amortized cost, subsequent default	29	27
Single-family | 15-year or less, amortizing fixed-rate | Payment Delay and Term Extension
Loans in Mortgage Portfolio [Line Items]
Restructured loans, amortized cost, subsequent default	0	0
Single-family | 15-year or less, amortizing fixed-rate | Payment Delay, Term Extension, Interest Rate Reduction and Other
Loans in Mortgage Portfolio [Line Items]
Restructured loans, amortized cost, subsequent default	0	0
Single-family | Adjustable-rate
Loans in Mortgage Portfolio [Line Items]
Restructured loans, amortized cost, subsequent default	4	4
Single-family | Adjustable-rate | Payment Deferral
Loans in Mortgage Portfolio [Line Items]
Restructured loans, amortized cost, subsequent default	3	3
Single-family | Adjustable-rate | Payment Delay and Term Extension
Loans in Mortgage Portfolio [Line Items]
Restructured loans, amortized cost, subsequent default	0	0
Single-family | Adjustable-rate | Payment Delay, Term Extension, Interest Rate Reduction and Other
Loans in Mortgage Portfolio [Line Items]
Restructured loans, amortized cost, subsequent default	1	1
Single-family | Other
Loans in Mortgage Portfolio [Line Items]
Restructured loans, amortized cost, subsequent default	25	32
Single-family | Other | Payment Deferral
Loans in Mortgage Portfolio [Line Items]
Restructured loans, amortized cost, subsequent default	14	14
Single-family | Other | Payment Delay and Term Extension
Loans in Mortgage Portfolio [Line Items]
Restructured loans, amortized cost, subsequent default	7	4
Single-family | Other | Payment Delay, Term Extension, Interest Rate Reduction and Other
Loans in Mortgage Portfolio [Line Items]
Restructured loans, amortized cost, subsequent default	4	14
Multifamily
Loans in Mortgage Portfolio [Line Items]
Restructured loans, amortized cost, subsequent default	5	0
Multifamily | Payment Deferral
Loans in Mortgage Portfolio [Line Items]
Restructured loans, amortized cost, subsequent default	0	0
Multifamily | Payment Delay and Term Extension
Loans in Mortgage Portfolio [Line Items]
Restructured loans, amortized cost, subsequent default	0	0
Multifamily | Payment Delay, Term Extension, Interest Rate Reduction and Other
Loans in Mortgage Portfolio [Line Items]
Restructured loans, amortized cost, subsequent default	$ 5	$ 0